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You can
write your own review of the MFJ 93X0 Cub QRP xcvr.
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K9EX
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Rating: 5/5
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Dec 6, 2007 18:46
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Great Value with Hot Rcvr
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Time owned: 0 to 3 months
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I bought the 80 meter version of this kit about a year ago and I just got around to building it at the end of Nov, 2007 (it took me just a few hours to build).
I heeded W5ESE's and KD2DL's collective advice, below, and upgraded the caps and final output transistor to a MRF-237 (NTE341). My unit puts out a respectable 3.5 W and I have really been enjoying using the Cub on the air, making numerous, solid contacts with it in just a few days.
I think 3.5W is just about right to make the QRP experience downright enjoyable - any less than 3W or so and you're definitely in for more of a challenge so I strongly recommend upgrading the Cub's final output transistor to the MRF-237 (NTE341).
My unit does indeed drift, as noted by other reviews, but only when transmitting and only just slightly. Allow at least 30 minutes for "warm up" before you even consider using it and then expect some drift when you transmit.
The Cub's receiver section is extremely hot and outperfoms my trusty Icom IC-718. (Of course, selectivity/strong signal rejection is not nearly as good as the 718.)
Very strong signals overload the Cub and can blank-out the receiver temporarily - you'll get a hint when you start to hear clicks on strong receive signals - about all you can do is adjust the tuning slightly and/or back down the volume.
Despite these very minor issues, the Cub is an easy kit to build, a great QRP perfomer and a superb value at its price point - it's exceedingly simple to use and has an extremely hot receiver. It all adds up to a ton of fun with a "back to basics" sort of feel to it.
Highly Recommended.
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AC0CL
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Rating: 4/5
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Jun 19, 2007 06:29
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Cute...in a Macho Sorta Way
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Time owned: 0 to 3 months
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I built the 20m version of this transceiver with my dad as and early birthday gift for myself. All in all it took about 5 hours to build, test, and align.
As noted, the receiver drift is pretty bad when you first turn it on. If you warm it up for around 30 minutes it goes away considerably. My complete solution is to leave it on all the time, since it's QRP w/ little current draw it doesn't cost much money, and the drift is not a problem.
I'm using it with an 80ft. vertical up a tree out back. I'm consistantly getting great signal reports. Mine puts out about 2w.
One small drawback with mine is that when the QSK fires up with my keyer, the initial click is deafening unless you turn the volume on the unit down. If you can get use to turning the volume down each time you need to transmit, it's not a problem(I'm used to it), but watch out!
Aside from being a cheap, decent quality, QRP rig. This thing is also incredibly cute sitting on a desk with a set o' paddles next to it.
Overall, MFJ did a fantastic job keeping this thing cheap and easy to assemble.
73's,
Jessé, AC0CL
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AB7JK
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Rating: 4/5
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Feb 15, 2007 01:43
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It works - da!
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Time owned: 0 to 3 months
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A pretty nice offering from M___ F___ Junk. The 15 meter version puts out a watt and covers 21010 to 21070. It has a thumping sidetone and some drift but I can live with both for now. I'll do the cap replacement when the band improves. I've easily worked a few South Americans in the afternoon with an all-band doublet. It has a nice AGC that the SWL series lacks.
Nothing to wright home about but it works - for MFJ that is saying alot.
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K3MD
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Rating: 5/5
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Sep 2, 2006 16:27
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Works well
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Time owned: 6 to 12 months
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Purchased th 9340 assembled. It took around 3 months to arrive... I had forgotten I ordered it! It works well, and just as advertised. I do not find excessive drift. It is a lot of fun to operate, and adds to my collection of 6 other QRP rigs. Only the Wilderness SST and the Small Wonders Labs Rock-Mike 40 are smaller.
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W5ESE
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Rating: 3/5
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Aug 19, 2006 14:39
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Fun little rig
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Time owned: 3 to 6 months
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I built the 9315K for 15 meters to have for
Field Day 2006. The assembly was pretty
straightforward, and the completed rig worked,
but the VFO drift was intolerable.
I studied the schematic and compared it to some
other QRP kits I have built. I replaced the
multilayer VFO capacitors C6 and C9 with NP0
type disk ceramics, and that tamed down the
drift alot. (These are also sometimes called
C0G type caps, and have a very small
temperature coefficient. I used AVX 50V 5%
part #s SR215A151JAR and SR275A100JAR, mail-
ordered from Mouser, which easily fit in the
space on the board).
The drift has not been eradicated completely,
but it's alot less than it was. The radio is
now very pleasant to use.
I hope this information is helpful to others
who may have built or are considering building
a Cub.
Adjustment of the frequency coverage requires
varying a slug-tuned inductor; this is a touchy
adjustment.
The MFJ Cub is a tiny rig, and would work very
well as a camping or backpacking rig.
The assembly and alignment is not difficult.
With a little guidance from a more experienced
builder, it would be an excellent project for
a QRP beginner; just make sure to have on hand
the NP0 type caps for the VFO!
Scott
W5ESE
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WA8MEA
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Rating: 5/5
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Jan 12, 2006 09:26
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My 80 meter version...
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Time owned: 0 to 3 months
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Since I build stuff all the time, I didn't really care to be hassled with having to put this together during the holidays. So I paid the extra $$$'s to have it arrive wired.
What a dam nice little rig for the money! I mean, we can sit here and be critical all we want. But for around $100, we get a pretty nifty transceiver!
I get about five watts output from my 80 meter version. Someone answered my very first CQ. He couldn't believe I was QRP.
The receiver is better than my Sangean 818 w/ dipole antenna.
Yes, there is that 30 minute warm-up period to avoid drift. But....I turn it on right away when I came downstairs to the shack. And before I know it, a half hour has passed and she's stable as a rock. At just a few ma's of power, I leave the lil' cubby on all day.
Hats off to "Mighty Fine Junk" for another low cost piece of FUN.....
73, Bill - WA8MEA
http://HamRadioFun.com
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K2JN
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Rating: 4/5
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Apr 16, 2004 14:31
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Good kit but poor customer service
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Time owned: more than 12 months
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I purchased a 9320 kit in the spring of 2000 as a birthday gift to myself. It took me roughly 4 hours to install all of the parts including winding two toroid coils. Installation was fairly easy since all parts are soldered to a printed circuit board (no wiring is required) and all of the surface-mounted components were already pre-mounted. I encountered only two issues in construction; the SPDT switch pins were bigger than the circuit board holes and I was missing a 220 pf multiplayer capacitor. A little bit of reaming with an Exacto blade solved the board problem. The missing part was not so easy.
I wrote MFJ an email about getting a replacement and they responded saying that the capacitor would be mailed that day. However, it never arrived. Follow-up emails were met with silence since they refused to respond. Eventually, I picked up a replacement cap while on a vacation trip. I’ve owned several MFJ products over the years and this was my first experience with customer service. I was disappointed over the incident -- even to this day.
Once the kit was complete, I found that performance was as expected. There is a slight RF drift but it tends to stabilize over time. Overall it is a fun kit to own and operate. I hope customer service has improved.
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KD2DL
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Rating: 4/5
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Nov 12, 2001 21:12
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9317 & vectronics 1320 1330
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Time owned: 3 to 6 months
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I just built the MFJ Cub for 17 Meters. Two things worth mentioning are the radio
drifted slightly lower in frequency untill about 30 minutes warm up time.
Bad enough that I replaced c6 150 pF with a silver mica cap instead of
the supplied 150 pF multilayer capacitor. That cut the drift down enough
so you don't have to chase your qso up and down the dial after a 5 minute
warm up time. I don't think the drift will ever be totally eliminated with this design
but,you can improve it significantly. I also changed the output transistor to a
MRF-237 (NTE341) or (2SC1947). Actual part was the MRF-237 and was able to
get about 2 1/4 watts output vers the 1.5 watt output with the stock 2n5109
supplied with the kit. In comparison I also built the transmitter bords from
Vectronics (also now MFJ) the VEC1330 and VEC1320 30 and 20 meter
cw 1 watt transmitters as I already have a nice travel radio to recieve with.
The vectronics kits were much more stable with little or no drift.
The MRF-237 also increased the output of these bords by 20-40% depending
on freq of operation. The MFJ cub for it's size a great travel rig for
17 Meters; however, for 20 and 30 meters I would probably build the vectronics kit
instead as it is far more stable but only offers 10 Khz tune range in the CW band.
The 2n3553 transistor did not increase output sufficiently to justify swapping them
as suggested in the MFJ manual. The gain is appearently not as high as with the MRF
family of transistors... and obviously the higher in frequency the less power they all
put out. (your milage may vary) 73 and Good QRP DX de KD2DL
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M0CQG
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Rating: 4/5
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Sep 10, 2001 04:12
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Fun little radio
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Time owned: 6 to 12 months
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I bought the 40m version of this tiny QRP rig. It took an afternoon to build and test - a very easy project, certainly within the capabilities of any beginner. I did feel a bit of a fraud just 'finishing' the radio off - it comes with all surface mount components pre-installed; you just install the bigger discrete items and hardware. Alignment was straightforward, and the rig was ready to use within a couple of hours or so of opening the box. On air, the RX performance was surprisingly good, given the relatively simple design. The TX signal received good reports too - no chirps or clicks were noted. After alignment I measured maximum power output at around 2 watts, but adjusted it down to 1.5 watts out of kindness to the amplifier stage. Even with my indoor dipole, this proved enough to work UK and European stations with ease.
Things I liked about the Cub:
- Nice quick project, perfect for a Sunday afternoon or weekday evening
- Great quality board and components
- Compact and well laid out; looks cute!
- Performs well for a simple design
- AGC is excellent!
Things I wasn't so keen on:
- On 40m version, VFO knob tunes 'in reverse'
- No RIT (though mods are available to implement this)
- As standard, comes with 'phono' antenna socket (I fitted a BNC later)
- VFO drifts rather badly until fully warmed up (OK after that)
- Paint finish on lid was rather basic!
Although not perfect (what rig is?), this is a good little kit. I sold my 40m Cub, but was smitten enough that I'll probably build a 20m version some time soon.
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G4GZG
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Rating: 5/5
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Aug 27, 2001 12:58
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Marvellous little rig !!
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Time owned: 6 to 12 months
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I bought the 40M kit last December, on an impulse and put it together in about 4 hours. I nearly wrecked it when testing it by connecting the power the wrong way round, so the protective cct definitely works !!
I found it easy to build and all the components were there as described. Mine put out about 1.5W and I was going to adjust it but never got round to it , and run it at 1W O/P.
On air its a dream - -if you can live with the lack of Bandspread tuning - -I grew up with old WW2 surplus rx where 20M was half a turn on the knob wide !!
I grew to really like this little rig and worked some good 40M DX - - VK, UA0, W1, VE3 and PY2 using the Cub and a 40 M dipole up about 25 feet. I also had a lot of good EU contacts on it., and every contact brings a smile to my face when I remember the power I am using.
Some other users complained that their Cub VFOs drifted, but mine is perfectly stable after a few minutes warm up.
MFJ have a winner here - and the semikit idea is great for the returning homebrewer - like me .
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